1. Field of the Invention
The present invention relates generally to linear motor systems, and more specifically, the present invention relates to linear motor systems including sectioned stators with thrust compensation regions.
2. Description of the Background
Linear motors may be used in many diverse environments to move a thrust plate or runner along a path through a linear stator, often travelling great distances. Several useful applications of linear motors include elevator systems (with the motor oriented vertically), large door drive systems (oriented horizontally) and projectile launching systems (oriented horizontally).
For shipboard and other space-limited applications, it is desired to use linear motors as part of elevator systems. For example, an aircraft carrier may have ten or more elevators used to transfer weapons, crew and other materials between decks. Because linear motor-based elevators can be designed as open lifts (without cables), they are suitable for carrying such varied cargo and provide for easy ingress and egress onto and off of the elevator platform.
However, to prevent flooding or to contain other fluid/gas transfer (such as a deck level explosion), the elevator shafts in shipboard applications typically have hatches that seal the elevator shaft at one or more deck levels. In the event of an onboard emergency, these deck hatches may be closed to contain flooding or prevent contamination to other compartments or decks. As a safety precaution, during normal operation, these deck hatches remain closed unless and until an elevator requires passage through the sealed area of the elevator shaft. Obviously, having hatches that seal off the elevator shaft between decks precludes the use of conventional cabled elevators in these shafts.
Although linear motors may generally be useful in such areas, conventional linear motors are also not inherently suitable to use in these elevator shafts. Specifically, a linear motor operates by selectively energizing the coils of a linear stator such that a thrust plate (and everything attached to the thrust plate) moves along the stator. Gaps in the stator, however, disrupt or stop the movement of the thrust plate. Because the deck hatches must completely seal with all of the walls of the elevator shaft, gaps in the stator (attached to at least one wall of the elevator shaft) will necessarily occur at these hatch-sealing points, making the conventional linear motor elevator inoperable under these conditions.
As such, there exists a need in the art to provide linear motor elevator and horizontal movement systems that compensate for stator gaps and orientation difficulties that may occur in shipboard applications. The present invention, in at least one preferred embodiment, addresses one or more of the above-described and other limitations to prior art systems.